SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '362de15a7e987e2dc6347e027739abfbbae46e48cfd972cdc82e96a4def0b78a' 
  AND token = 'U9zMU73UybpVB7xoLfeQbFu/VZudVwfB9/qaL3xmRRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}