SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e1cc8ad960be1456c1db30e490c752e4d5c91092865e303ea7c0a9cf0f7cf46' 
  AND token = 'dScwTBl9Wz+tYki1Y6ey8xJtzHzFrYTHqzIjlixYLdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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