SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f168e5327300632a377ff9af7659dedc093a6d436ee8731a80110bfbfe203105' 
  AND token = '71UAtCrRsYKY8hJCoEezlqjFQm/gFD6x5bQVpzjAAKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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