SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6d470014dc7871576fde0c463260e9275e87f70fbe50d1644d4685903f77851b' 
  AND token = 'DGK6YWWP4tup6EvwZiXVybK0RrewNRjPePGCfjxkRIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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