SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a8b13ba7d12cbe8c0a7dc8b78ea2e50a6fa94942d31053418c8c48ad84b33e5' 
  AND token = 'K9B7o+j1Ubj1Xqv+yptySQ8IxD6+EfjE8afLa8bfOTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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