SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2438ac4f55d520dccbf4919fda20549623f7cab596103da9c493c87bf8538310' 
  AND token = 'L+csuMsxbN/yz/8jboY/k9QYpgHkV5DolNVmDnLKWvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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