SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec48e32ea3264ce7a6a8fef1ca0ff7fa6032f0d75fd97b673946dae09aa24578' 
  AND token = 'LXMUnv+vIWrAyFnArd5/kw1q9YmBtB/sm08ksJt9rww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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