SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da8d54105a7772db323e80997f70131f9891a706fdacad5f6088507ad64f587d' 
  AND token = '1vi3ZxAwADeTQH5DyZ8u5kM73cplUo9wIGJz+Gow0GI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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