SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e943814c8f56608688acf752b564c514a39df4b3b5d4d95831c6adbab5dbd2d' 
  AND token = 'NOW/dRhxryFqAOruTk2FXwECEG5Q8aaJZ6ft/LnyK+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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