SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b18ebf5af8464a31926ee30893d58d39d04e4207a25155e98fe012727ec0409f' 
  AND token = 'iDv0GMtW00D4SCUaK/27hQAp1CdQNEuoDeD4/iSbgyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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