SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '296706545f464ad167e378535255f8e59a1e6988ed9345236effe3031966436f' 
  AND token = 'a2tXg2PnIR/jy7jYpAieNzxHzlkEnH9IMJ5S9YAc7Fg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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