SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8f67933c4e8778444f28f271c1a2debd307c402cb53d6a90e736fa610b99532' 
  AND token = 'SHVI7hbDOG14VJ1p1cQ0rnDrg4gryLZP/NoQMJqfZmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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