SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02771b0077231393f32cd22e4afdca95813a5a4b7e9fd9382c4f0efb5d7d3790' 
  AND token = 'o2Iq4HAsRtJIKtYipEj6/5mw91lhAKwDtkLBu+ocPT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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