SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab73a3a7f23b1a5509f99d35bd72f36d9912cf2f6411280091b9188f658c8484' 
  AND token = 'AikxlSlZcHEY1usXSQFnOGjd4sKS4UmXuE/iV7RVFmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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