SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a9ef543c90715913588649d7a80f9ed039705e26612599d7e06ac1af1b39ef2' 
  AND token = 'KRv9L2PTW7CKkJFZW+V4phdDDYrzFY+dlxySwN22LRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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