SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4251d59c13901195db95f885b1b6e7551b968cf98efa7bba6e323b74f910d16' 
  AND token = 'QrzrHtYm1gBrMilC0NTeg7UerF0UNiJq6FPA2ferUMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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