SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de11765ec647995d7c5a59397dd490c04754b049d5212f637ac3b709bca857e8' 
  AND token = 'KKuOLxENWgrftzoqWMzH3eBNd4fxMeltqbWtJ75jWms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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