SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b3f132af6498a23345186f492d6995505304c702dd6f03307887dcdeebdf23c' 
  AND token = 'iufWbdHZKTyD+tAfy748ijst8WHp9Kr7PeqHkFZZ07c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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