SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ff38136ed58a34cf23b5feaa5480e527f157d08def75fdcfd702175520efa52' 
  AND token = 'KvzzVIwiSoRoB4oqz6zrG/NBQNTucPUiF2qPWnPXyqE=' 
  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"
    }
  }
}