SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4b3820c85df70f8be2c5daac374a0fba017006d34544df9c6bafda0c1a0aaa0c' 
  AND token = 'F1alqQTj+DKr7TLYZ67ieRl/TzOSNST3coN8hYiemgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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