SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d2b9da74bf32844afc1f9c359b7192e7db59306efd4bce65b9b47e2386bffb' 
  AND token = 'pdRQLTM8ZdDfT096dAfFVlnPVUx3ho7JYQeEjeFQ+VI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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