SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c7d138a1f2656b7446b38aace32df5d6127dcb83926574ffb48513a9d9f5b7' 
  AND token = 'A3DU2eKIrB5o+WA/imSIRIjFJX1gnHI+zWGwcgYTVHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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