SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3576dcc87ce0f8e10634ad664f858d02f4de4ff710333b91469af94f654142ef' 
  AND token = 'vlPUE6xUghCRdvekbd/tErWEIbaeEXs4bHnDP5NI5h8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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