SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c52b3873ef3fbd6eb692a78484132596577845645d247f74982cab094e8d2664' 
  AND token = 'ITgB+MdP2Z2mphAqWzCrU6Cfg+E5ehdoOH2jvaZQ/UI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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