SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '450331af0954ab9d15d3d5bbee108d4bd6ff88c5413f9f95e2edce9480484bdd' 
  AND token = 'oFRrtxEvYrKOiWUYCuCwQuUFBJuzvK8Qc2Hy4C8WRoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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