SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b59784bfd06ab45b9c22989729a4809afa940a679bca63ce34f5b0ba05e4dc16' 
  AND token = 'WSQsmfhkHMK0YbtVIXbCQ2XgbNI5TGj3vtmzLmsk28M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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