SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6bce8042725406b44e90f91019b6c4ff5330e2b405980d5e9aaf098f15e20ea' 
  AND token = 'iBEafOOPq7RzuKtHIWRIDh5VYyIsobOQul1QgMFCifA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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