SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c72cdba32e192990016b18b998a6fe8ec477f5965a25eb63e1045cd2864bf7f1' 
  AND token = 'nN+Tle8YAIVxL0EGDLg1E1KWzCmRIrd9hr1k/qjs6RI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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