SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f0cc86595a32ff8cdd41ddce8eea4eb8f8c9cfb156717b7afd4468c5a605b16' 
  AND token = '/RPHdzUjgk/tCYGFYfZhECSjSmkjTw57GOASJYPrjpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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