SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100ee420ec70efc603eba0fedc99ffb9506995fbf19e80d741c239762a85cdcc' 
  AND token = 'F3w7jxlJTzOk7vsANmdOe8zUeYeUl30tQ2DuVNR8/CI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}