SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af702477b0f144427816f371b811a7d2239a086bb216b17c6b5cc3b74494ad1b' 
  AND token = 'T+yxhpDA8YHBo1Z+M7KNJtnjFGAyqFOYGmlUhWRufHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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