SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b2e5de52c7413e70b411100e7615b4d74a370c9e8fa1906d1481a6c0e90e0046' 
  AND token = 'rxAf3sF+wtNbleV7SxRBkqvKVkJqOFjrW/jxrjUMW6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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