SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ffe4dfc40b1fcf7ac175af65348a72127a8844f621bfef00fb8c3feb388dd0b' 
  AND token = 'sE3l4oHF6ZimVKKlAVf7NpIaVyUbMcydIkBUiyRMsiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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