SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2758aae34a6cc2477990942ae325e5ace68730bfed36c8f00a19874559ba8119' 
  AND token = 'f9YBKNGf9+GkvtHjizJXuZ5N79xXbpPPkmBADZXQ1F8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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