SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb323e97c174fb1b42e600895b11d87d9defba7cc1a9c82d96265e40225d9bf1' 
  AND token = 'd9HYNwDysDKIjNihSQus1xnFxacoEJe/UfMPgBFBkGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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