SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6261ea1545c71307a34eadcefa5f665119a26d2de3e4a67ea9cda50c58f63f45' 
  AND token = 'CpeTd/Hw+BUyztvuZ3M2PrjmGWxvOYzK7yNu4TyanxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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