SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b594d4b0a7ec7fb274f9aff72ed1f2ea80202470be24b685829f7bede3b74774' 
  AND token = 'KhSdYMavo+HqtwYh5z3JeNmdnJFzQdCkb6J5cqKsz5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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