SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bb48b3eab0862463794d2fa54c06757808ec49c7723ecd70c1dd58c8d2c9c14' 
  AND token = 'DmI2sphdp7up1xllPoVM3dYO6IxBvrGry8gsdgnDUA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}