SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '880eed58370beaddd1b87328745f33fe28fee44276cc4fb95756999e1ff7c313' 
  AND token = 'tUUdOJKkRd8qLgpzQ/SxoNA3Tis1Rbdn7xg28lPeAG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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