SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '507d460ad5c68abf6916f99470eff09b7ed2dfffa72f7f4c20887246fe90fec3' 
  AND token = 'LiTKMvBzZsIFCS7fzsg9thGylH0hm6SIM+/XCVLCfVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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