SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3534beed3d33a88a0da93f930121761b0538eaea6357b6ae941e11c418ef3cfb' 
  AND token = 'fTBx26PCqmfx6xkF5qDrdNLbIMIwsd+iWn5Yoi84cwk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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