SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '07b46437f6b43f22d4def3603d4292d0e4bd9eb3fdf91619e36a0429d04605f2' 
  AND token = '5+g+yP69UeGQ9it4vcUo5imdbMjqz8XMiy35WzhCysE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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