SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51a89de2471679d5af676f231ce196f17861ab11c970fb438b02c1399da55680' 
  AND token = 'VjDiesp0zSU3zbxhHzB6WK2FyJIfYebJbMjJFU1Sd6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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