SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '686d9a6979a3b4eb695537e40986993b753caa91965c5497754a15b026db6a5f' 
  AND token = 'YQCWLEooNEaMAdRj7y+1f39sLrqLqBfrufjumKISXGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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