SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab42cb07af33bb7b7665c6b060fd3de052d946c2f8c8baf5e51c6f86266fff46' 
  AND token = 'ysTAKMNJ5RjcCkztrCv2bDMu4aHFt87tkduc9+a7mUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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