SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd5f5e1d9b31ef6be5cf07c967738355a94739dcb1048a94b8ddcf0670336086' 
  AND token = 'siR3oSYzHlpNPbP+2+wxDc8OvjcGLn9uJLaQwXihG9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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