SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f8e9b096e69dbe600c1d4cc9643bce76fb5d8ebfe48c153ebed30223d14eda' 
  AND token = 'smean7cTYuemJWtgMTjLqCEPUIcpxJayMEJ/J1fICb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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