SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0d66d3223229641eaaeda7a65e48a5d831c13c65a66f13675488ab267adea96' 
  AND token = 'yeK0WMd8naYklun7C8lBElweoTgjDfxg7iIC+Nl+ugY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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