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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a0a06df8be7d494eaa2628abb259bf8a9c1d9296533b3a4035207ccbefecf21c' 
  AND token = 'j1+TVrXS3/k9Eh+VMqa5tAcBTjguBGOkIkicVcCndjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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