SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dcba363ac57394468096505f3e4cc56a5fe64dd2f824db95679218972222287' 
  AND token = 'u6CiW6TJksDWh+VH4ydtzBTHdSe3jMFYfdxV/mvuJvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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