SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3637aef982629135dafb181f3ed2b90c88b39bbe1d07aafecac200c3681dcf6' 
  AND token = 'iC8DjoxBuKH43vWfaZ31ekyouvh+lyfqOVvUxYEJomc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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