SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '738547cd54f6d8dceea6238980b302352724a969414a8582da879bd8d84ece42' 
  AND token = 'lvsKUcPfdHMnspE3gtLWUP4yT8kjmANzP8p9wF3x3mI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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