SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '582631605f86cf77b96fab523134344f98996f458ef54db15365e4241594f69d' 
  AND token = '4v0+Rh2gqk2KUyAsB0pimvzr4yRoRF+Ngm/3nQjrMuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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