SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7be707cbd497d89fea793e83e3689d5029a2bba9671ad3b5137945daebea781' 
  AND token = 'cANnnnbO1y3G/FAEefXjmpVRKGro0pmlKJ+CCZmqg+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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