SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '581a57e9dc2d64d8f1d85233a3198e357ca98c93a55a58f0be23df12959f5f0b' 
  AND token = 'bWZJyKxQmuHUVHyY0HeVltsudbgTV7IkQnPk2AL7nc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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