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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '394793085e5dc4a09b7d86a3ed0e8f886b400c5d67e3e4bdccc5f981dbdd21ae' 
  AND token = 'UKhQbi5xEz1mrttbRUGPr48fBmZ3lnAtf8xBMZLj4oQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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