SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '126fc38a01fe76c6842ea57ae076551528481ae30bbafdbe47563849e6040e5a' 
  AND token = '40OWJq0YqpTaEfdUK9Z757r2ToloYDCpvhXhYl9p3Qo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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