SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb1d103c1fcb198d933d09033d17aea52fecf397f6af28078d37fdef6c36b182' 
  AND token = 'MtjJ78+po6xN+nwPjksUsbCHSxPX4Smq3aQDqQhmsMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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