SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '475dfcd611851d43fe699e09f9ac3898166f03b45d88ee5f2cd489126d578f52' 
  AND token = '5pGsczbaRUXB/uX+2RZRfA2oTTkmxv3wsd6uBW0+gPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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