SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ded5640b25de94445408c2709caa099d26c7bb14fb6a49135448470e45eba50' 
  AND token = 'tvQhpW1v9mk5ozB235aMJ8pGpYiOJtvNGPnYVbjXMf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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