SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '940c940b4f878260ab049904bda4a937935c3109cced306108695ca7fc3615ee' 
  AND token = 'BMZS/ZfCwVna1YNyaJvIWMq39P3TXYi60OTlH8/jJbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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