SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d0a118b8d8af7beb78ba77c1c6a273f5f4f543034171b8121709234aadfb3d6' 
  AND token = 'I4zLNvkEUtH+RbcLNNNRofrAMWXzxOWmXzSwLlfKin8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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