SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4261973ba482fd252c13588e190eab7ce897402337ca0da8e47637ff65e3f21f' 
  AND token = '/CCHsIx9+CDcNr4uhmKNzQ5t8AAx3/TfE6vsqmB0cJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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