SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e35f1e503977e82397dc6a1e106c3019e8e93b81d3b86880dc1c87b62c743bd2' 
  AND token = '9jxmyS0dwvlm05lp/XGxqy8xsEYUnRxgUM/LcS565VU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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