SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39944bb73053aa74985dec436d15ff966f8f670e40c1f38355361a247d8ae9a3' 
  AND token = 'RLyUxynPU9RimgA624YLpIU0cZ/awo0jOJKcdhi6nIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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