SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5bec712081adf33cdac8d49b6e08bc15186c02ff5b93c16db951e3f8dae212b' 
  AND token = '/WRMloMVuaCoZDmnS8fZBwjquwTsH+ZwLSci3BMSofI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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