SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0db78214c0263cf06465574940ac046be962a78c4ae7ec8911322d894dd017c3' 
  AND token = 'n18ZVMKU++YSE+I1o640aMq5zFRdHUA5OFSpHnviuH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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