SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6715324e1cc3770921c49d1f2aea0da21374e410382b4c62a27d4ab0c926ed3f' 
  AND token = 'W4ik+wPCZbBcQrWdrJC1ZMnUO7yCFcmCpNV8Zi5ZR04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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