SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc36086ed4536e8e7d97f16e62c718308ffe53195c52664ff6db920259cce6ed' 
  AND token = 'cDwo7IVGr+GcNrrLSmhXaHmaMKL4xJAVfFd2EOWmWBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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