SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '259c262d89716d159b709b6898005201caceaf59afff3c8126e85736494437a8' 
  AND token = 'ziXe+NC8297dF/7W0gRM76vK+uzzqVpfNdCIuP+9gY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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