SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7d6137685489b60502f92301395f5d2568d37f51516e33015187e34432cf7b0' 
  AND token = '52pnc0kNopbIKRwqrtrQoLi4YrzIZJqiRSg+eAIqwwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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