SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e15157bc0f922fded0450a7caddc3a66d81884814c58b52d15863f8f59add50' 
  AND token = 'uG5TQv18iVTOWfw1SMP1q+zNOxKokRzhMqSdOBKn9JU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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