SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb08fb70be07e69731b33bcaba4412721aaf2e2d6dcf6f948e540cae800710ab' 
  AND token = 'J4gJbltxiN5ovlzjzF/MCvcdl2Mh+QFC7prpzYQ7JSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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