SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73571f06e5a4b86d74da6f0b5d753892d932bd5218f1066e8b0bd08f2b88a425' 
  AND token = 'fI71fQr/3OyYvxjQQ2S/gVJqNVnVPBlnovKJFS6zSVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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