SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e6a38a69a08f6656f05d0fef3104b1fce485bdedd2ffd38f2944c6cbae2dabb' 
  AND token = 'tDYl4Q9KZgoVVFZ2l7+5F7Jc9QlMgBZiK96jzhnF/l8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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