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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d1f17555c59d49db60f29237508693de8108c65fc60f7d8009f041f834b9fdc' 
  AND token = '3/vBRRX7/ExyZvjPNHrh6DjqPAUkr6HIUi7vBvFm/OI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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