SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23d1b013c22c01fb5b7fbceccf7258e5f146dc415bcec843ada5dacde221bc80' 
  AND token = '3kZitzbaXO74gn6ICD3e7j86QBPDICWI4aePc2TOzTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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