SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a4e19fa0c655e43538bf73228a39a3d2dafac6e451644eed981794cdaa9fca7' 
  AND token = 'amXXLxvS60LlHybcWUZxPUOkJnv47IHeTCHJ8SARijI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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