SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '396f7f492ea1289c728d6c029493334641b47b0758bd649643add207a6c52b89' 
  AND token = '3h5MFmnroF+Kzv9Xq8J8gT8VQMRqGvyHk7p7E3DqdWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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