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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2dc3bd9c420b950d1447da52f3b23d32e084bb43a014baa27982ccfa2ac4f76' 
  AND token = 'b6f98b3RajmHIkMGnbeDPIn8Kjpu5Wj/EHuwU2Z5Oho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}