SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f1e356cf584b37972f26467fc6c8353a32f8eefd6e5f3c0752ead99d21eda11' 
  AND token = 'PCw+LawSh+BPPaX9AONBTLpK3OQY57jywRJzLoCQoSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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