SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '843acd67b4b86eea761287fd74eb78d397b172aa1720b0fbecd4fdcac28d1508' 
  AND token = '0MZSGSIVb3uGKAF4wbAJGY8CkSENl6hZiOEcsgBhEBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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