SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9b67aca9708e5de99252aad1eb695991370fec8c980c3435238afb3f1a2973b' 
  AND token = 'AJTOVtDjR4G/jl6xoDJpjTfRwYafwDL8SzIV0H252JA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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