SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98140205da362281ea66490888431c238b239916eeb35e618679f7784b585f3e' 
  AND token = 'tRkgeAZfOemcYHQBnX2bDFSjcRGFchUg32Lg+gtX3xo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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