SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc436f551554d0112808ff941044203199db5fcffd16b30ec24d8e56d516810b' 
  AND token = '9gcrHBZpD3ghbgIb4A0kpFI8MNAGc9iNCqcAIpD6nf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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