SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebee6d6d29b9534c889bf15b8bddc5a0cb87665afabec1c8e3909e7d761a8321' 
  AND token = 'wEAn5056dU/rNDA1IyAEQKNA2gvuzMXisE4IlwjRhKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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