SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a47d36ef4096b4b766be1737b9731060b8944752f7e14f573918230f8401f954' 
  AND token = 'fzKBpnuUyLrfwZvLpQCWJg+M+aR3q5bOZ/+qaQVK7iQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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