SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b78ce615ca99d8414d25764ee12eb5dc4f92af988095becf5acc533f0fca2c5' 
  AND token = '9blAmrv8Cb1GnRu8XFZssOhP6pWofUJLjjFdIPYAkA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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