SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e39a44b9c6a7b33784ad6c1185d7f71e4683d97ea8d7708520b0cce4ce75df8b' 
  AND token = 'PAAKRuB8EqhGiVR67GG+xLiadVlIjvAyYGza7clmIY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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