SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '378d2d399020121e24fb824deccf8a017e121734bfde1c23667fe8538810e56d' 
  AND token = 'AN0I4cClUvyZBsNYnTokj/rP0Mnh0GcjxJc4WaAYug8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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