SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1d616311c07eaee1ada918294343eef4a6fc55c988699a61c4db95330c4f660' 
  AND token = 'fMIbM5q6JBIiAsRae0GjdmR638mvsqhg+RgEGtWRBQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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