SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e7bca7b368793a02dab626a092a768d3647fa4c2eda0241b7bd6cbd19684b61' 
  AND token = 'pO2/kdZBIOr1Fg1L7yptfyeHk0G7U0R5NFS+yZcVrMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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