SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cd408c8c15a365b5e4b62fb079b406135accbbfcb715351941107c3c6444bef' 
  AND token = 'U1srZBfrtOq70NvU6SFqmvQr/wRVqCKtuRoxv+624SU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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