SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd055671f974367659780df5ed02a4dccec81a3130ff9d50f101132a878db276e' 
  AND token = 'gCjvXWEx1h2xmO499CCcTzsZWIVPTxQuTJ8cvTPALUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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