SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b7ac74bee2223f050d40277f8a2c0b55ec19f432a9a41bc469e458940946793' 
  AND token = 'TIuCAjMgg6JEGo/YUtPObCwIhrpjRjYNKUD1Hrkq6xw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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