SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42914794cc9143747c8c276accb6a290e9cb40286473323e849701e63902af63' 
  AND token = '8tzWjTAKq51Kz2NaJR7oSmDiA04EKTYpNEb5uMd9QUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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