SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ee3309829cc0ebeedebe625a5ec1fc42d84ec27a100a8d5f1238907f27982aba' 
  AND token = 'grxDcAJOc0UAwrN9kfREm+CPPxpzBMewH457yzM7oFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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