SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7deffe8e0fe42a7068c3d2611a88b0afcf0fba06505b44d55aa0ba5aa68017d1' 
  AND token = 'r/Z40F5rST8RsJ5XGeQdOdCcz0zbjCYl+7KskwtjEcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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