SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '994f6457dcfbaf7d313c1594992f7c078635d83d985cbb956f1058050d3a505f' 
  AND token = 'veSzoBXjkA26y34fi9qj42eWRGBfACs5T96cc2XuACo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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