SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5507abce558ed0e8fbcdc9c10974706a0b0d6b243e0e1bb745eef2cde6edc793' 
  AND token = 'cDd2IaEcaPJgafnxPIDHcFHJAF76FaDyTj2rCLn4NxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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