SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28ca107e2fb33f6477a871ff90eea1864d3d591159ee97588d0683864b2a784e' 
  AND token = 'zlLJqYatP+c/fDmyv2GCxDVOjgVEJuYMNjoAade6FHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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