SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19bbfa7204027b83706aaad45c3d96121324574774812337dcd7ca3e97771864' 
  AND token = 'DKPvMODAUgqMDWdFgjH3Lnjss65wBEeOfjlOaUCiFkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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