SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ffe4aaa3cc5535787a94ad811fff134ee288984d6014a7ddfc040174a1dcf86' 
  AND token = 'd5t1T8JwyjRYT0XjXB027ykS3kQY2n7kvxn2t2BsEqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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