SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6d1913beade22023e773d584cdd30e37446cda838f839ec57460d540975a44b' 
  AND token = 'RjJD6/5pK+lGdSQK2sd5ph9etvfmKRbMUrundVXpskc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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