SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a4a01048f4ab5ea4a257ea6365a54e0fef3ac5c4132648583f62722bf85fe604' 
  AND token = 'l6TAnDYFmYLdp8HIZeMxlBDOjzrVncp1YzcgIRFecro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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