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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acf0f8ba832598f03bc65b6ce04ac41a6934b835b4d1a60bc0eb311c8438282c' 
  AND token = 'R35Fp0sD+8OEtqbjUNpGcj3HRMgZVb9y27UHzeC10Xg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}