SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14535e1ab4f66b970f670148c1c34753b2f9bde5aeed6414835f965682296049' 
  AND token = 'zGFs+vQiikNiKBJSma+LvzsYZTqx9itYwawrnCENlv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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