SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f4c67bd85447f61dcbdffef441b608b4c30de7512d0ef2318dc6a54e514f247' 
  AND token = 'KnZXkDD8BQEhnK+4D168glu+NLrSeMRDbxDk/pv3KnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}