SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f7c658cab227d4233fc0ca1428f656c66de29ff5b3870be9d06a929f72cbd3' 
  AND token = 'iXa/dJQ47zVtRLIKZGd+kGMXHuq7vfgspNYQDt7DutU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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